'We are simply the extreme and fastest version of the principle of trading. Photograph: Martin Argles for the Guardian

What is it like to be commented on by over 60 people? The computer programmer at a high-frequency trading (HFT) firm just found out, when his "Voices of finance" monologue went online last week. We meet again over a Coke to dig deeper into some of the points raised by the comments; about survival of the fittest and downshifting your life when you have kids.

Quite a few commenters wondered how you could live with yourself

"That's right. I couldn't show the portrait to anyone at work, as they don't know I am doing this. But I sent it to my parents and siblings. They said two things: everybody hates you. And we finally have some idea what your job is.

Look, I am not ashamed of what I do. Others may choose to devote their programming skills to making the NHS work better. If that's their choice, I'm happy for them. Luckily we live in a country where people are able to make choices like that. You don't have to agree with everyone's choice, but you have to respect it.

Capitalism means trading on markets, that's what our program does. We are simply the extreme and fastest version of the principle of trading. The comment that we add nothing is basically irrelevant. What does a second-hand car salesman contribute to society? He doesn't improve on the car, he is simply making money from the difference between what sellers and buyer are prepared to pay.

A handful of commenters suggested HFT would fade away as technology progressed

Every few years some "expert" or another comes along to say we have reached the limit of X, Y or Z. They say that everything than can be achieved has been done and that we are at the peak of that particular field. The only thing all these experts have in common is that they have all been wrong. Human ingenuity has to date been endless. In fact, I find it arrogant to think that at some point we will have invented everything. With respect to HFT, in the 1990s, the critical timeframe for trading was minutes. Then it was seconds, then milliseconds, and now micro seconds. But it can never go to zero.

Another line of comment was anger at the financial sector generally, and the bailouts

Some of the commenters figured out that I work for a hedge fund, meaning we use money given to us by clients. Hedge funds did not receive any bailout money. They also seem to think that these traders effectively trade with a safety net because of these bailouts. Clearly since no bailout money is given to hedge funds, they don't have this safety net. Furthermore, the structure of hedge funds is significantly different to that of banks ensuring that the risk/reward ratio is better aligned. Hedge funds have so-called "high watermarks", which means that if we lose our clients' money we have to recoup all of it before we make anything ourselves. This is different at many banks, where every new year you start with a clean slate.

People seem to say, everything is the bankers' fault, or everything is the computers' fault. They tend to point to the crashes as evidence of this. I disagree with both. I think crashes are simply part of the system. That's why you always hear "the worst crash since". Crashes are an intrinsic part of the system, they clear out deadwood. You can't have capitalism without crashes. It's survival of the fittest and sometimes it's not pretty.

Perhaps some people might say, yes, capitalism comes with crashes but this computer technology causes more of them, and worse crashes than we'd have had otherwise. Well, you just have to look at the two biggest crashes in history. The 1929 Wall Street crash and mortgage crisis three years ago – neither of those were caused by, or made worse by computers.

How about the Flash Crash in May, when prices suddenly dived 8% for no apparent reason?

We still don't full understand what caused that. Did high-frequency trading cause it, or mitigate its effects? There is no conclusive evidence either way.

People might say this is a reason to ban HFT. Don't allow something you don't fully understand

As I said, there are many layers in these computer programs to maintain stability. Simply banning something because you don't understand it is foolish to say the least.

Take Fukushima. You might say, we need energy but we may not want energy from sources that are technologically so complex that they outstrip human beings' ability to control them

Accidents happen, that's how the principle of survival of the fittest operates. In Fukushima we'll find out what caused it and learn from it.

When the effects of a crisis are truly catastrophic, does that still apply?

We all know that California will be totally destroyed at some point by a huge earthquake. This is going to happen. Surely it's madness to live there – so why do people still do it? It's because until the earthquake happens, life is extremely nice over there. The benefits outweigh the cost, even if ultimately the cost will be their own lives.

The earthquake is a given, technology is a choice

How are you going to stop computers from trading? Where do you draw the line? Is a computer allowed to help you make a trade? What constitutes "helping"? Are you allowed to use a calculator? My problem here is that if you are going to erect barriers and make rules, you affect negatively the principle of the survival of the fittest. For that to operate, you need as free a system as possible. Only then can weaknesses and inefficiencies be fully rooted out.

I can just see the comment section light up in anger. Another point raised came from somebody who goes by the name of Lightfinger

"The problem is they develop a taste for a lifestyle in keeping with the job. One or two has gone and done something entirely different but the majority have found themselves burnt out, skint, physically f'ked and out on their ear when they stopped being productive. Two to my knowledge were dead before 40."

I hope it won't happen to me. Burn-out is a real issue. I play sports to manage the stress, I'm incredibly competitive so any sports will do to channel my frustration and anger.

Commenter Chumbaniya said:

"As a programmer myself I can appreciate some of the difficulty and pressure of a job like this. Actually creating the algorithms sounds like something I'd be interested in doing, but the maintenance must be extremely stressful, knowing that you need to diagnose and fix bugs as fast as humanly possible because every second they are in play they could be losing you a lot of money."

It takes a toll, and quitting in time can be hard, Lightfinger is right about that. The key is not to upgrade your life too much, don't let your lifestyle grow with your current income because downshifting that lifestyle later on will be hard. So don't upgrade. But then I have to choose a school for my kids. Do I send them to the best and most expensive one, which I can afford now, or to one that is not as good but a lot cheaper – so I can still afford it if I'd quit this job? It's tough, your wife gets used to a standard of living, and I know that regardless of what I do next, I will always be working very hard. So why not stay on in this job that pays very well? You can see how these things may play out.

Finally the funniest comment, by triggerfish999

"I worked in the dealing room at a big Japanese bank at Broadgate a few years ago. I wrote a load of end of day risk analysis reports (I too was a programmer). Me and an Aussie systems admin guy used to sit at the back of the trading floor and we had a ball. Watching the Forex traders shouting, and the money market traders bellowing at the gopher who had let the printer run out of paper. It was high pressure stuff cos we got it in the neck when things went wrong… But it was a lot of fun, esp on a Friday afternoon when we'd send sound files out to desk computers and play toilet flushing sounds. I mean stuff used to happen that could cost millions, and we were totally focussed on fixing that when it happened (we were good at what we did), but we also had a total laugh. It was good fun..."

ejam says:

I'm an evolutionary ecologist, and in fact there is much in common with many ecological and evolutionary processes with economic processes.Ecosystems and financial systems behave in extremely similar ways. They both follow well defined allometric scaling laws, they both co-evolve. The reason for this similarity is that ultimately they are both complex systems. Of course you can find differences too, but their emergent properties and responses to pertubation are very similar.I think this guys survival of the fittest analogy also works. Ultimately there will be differences in the detail but the idea that weak businesses and enterprises die out, and successful ones prosper and propagate, then speciate create more diversity and again, unsuccessful ideas become extinct etc. Processes similar to predation, parasitism and competition cause evolution of the system as well as the 'environment' of the globe. What is there seriously to disagree with?

JorisLuyendijk replies:

Joris Luyendijk banking blog Photograph: Guardian

Hi Ejam, many thanks, in a later comment you claim to 'hate' bankers too. Just wondering, is there an evolutionary advantage to 'hatred' ?

ErikBaehre says:

There are not that many anthropological studies of the financial world and this shows why that needs to change. A very interesting study is Zaloom's ethnography 'out of the pits', on traders in Chicago and London.